The present invention relates to orally administerable medicinal plant dry extracts.
EP 0 702 957 A relates to orally administerable Saint-John""s-wort extracts and a process for their preparation. Polyvinyl pyrrolidone is added to Saint-John""s-wort extracts, and the fluid phase is concentrated to dryness at elevated temperature and/or under vacuum. This results in an improved release of the dianthrones as compared to standard preparations.
EP 0 664 131 A relates to orally administerable kava fluid extracts and a process for their preparation. Kava fluid extracts are contacted with a carrier which is solid at room temperature and selected from polyvinyl pyrrolidone, cellulose derivatives and/or starch derivatives, and the fluid extract is concentrated to dryness at elevated temperature and/or under vacuum. This results in an improved release of the 6 main kavapyrones as compared to standard preparations.
The medical effects of medicinal plant dry extracts from sabalfructus (palmetto fruit), Passiflora, chaste-tree (Vitex agnus-castus), Crataegus, kava, ginkgo, nettle, holy thistle and/or Hypericum are known from the prior art.
DE 42 01 172 C1 relates to pellets containing Aloe vera extract formed by dispersion of the Aloe vera extract in a matrix which predominantly consists of a builder, namely collagen, gelatin, fractionated gelatin, a collagen hydrolysate and/or a gelatin derivative.
However, it is a common feature of conventional dry extracts, especially those which are commercially available, that the release of active substances, i.e., the speed and degree of release of the components, highly varies from batch to batch due to the natural substance character of the medicinal plants. Even competing products having the same extract declarations are often considerably different. The known pharmacopoeias also merely define the quantity of the components, but no properties which would be desirable for a reliable therapy with the extracts.
Therefore, it has been the object of the present invention to standardize medicinal plant dry extracts on a high level in terms of both degree and speed of release and thus to increase the safety of therapies.
In a first aspect of the present invention, the above object is achieved by orally administerable medicinal plant dry extracts, wherein the non-volatile phase of the extract is bound in a microdisperse form and/or in the form of a semisolid or solid solution to a carrier which is soluble in or miscible with alcohol, soluble in or miscible with water and semisolid or solid at room temperature, optionally in addition to other auxiliaries and/or additives.
In extracts of natural substances, which contain a wide variety of active components and other accompanying substances, it was not to be expected that such an inhomogeneous mixture of substances would be subject to much improvement of solubility in the mentioned carriers and thus to a standardization of release.
Surprisingly, it has been found that dissolving the carriers in a fluid extract yields an extract-carrier complex upon concentration in which the active components are bound in a microdisperse form and/or in the form of a semisolid or solid solution in such a way that the speed and degree of release of the active components could be standardized, with blending different batches, if necessary. The semisolid or solid extract phase is, in particular, a spissum or siccum phase which contains the active components.
The release of active substances from solid oral dosage forms can be determined, for example, according to the Deutsches Arzneibuch (German Pharmacopoeia) DAB 10 V5.4. When the release of the extracts using a medium which corresponds to the medium in the stomach was measured, a significantly improved release of the active components over the prior art was achieved.
Said carriers which are soluble in or miscible with alcohol, soluble in or miscible with water and semisolid or solid at room temperature (25xc2x0 C.) are preferably selected from polyethylene glycols, especially those having a molecular weight of at least 1000, polyvinyl alcohols, polyvidone acetate and/or polyvinyl pyrrolidone.
Polyvinyl alcohol as used according to the present invention usually has a molecular weight of from 28,000 to 40,000. Polyethylene glycols having appropriate molecular weights of at least 1000, for example, 4000, are commercially available. The molecular weight determines the consistency at room temperature. Polyvinyl pyrrolidones are commercially available, for example, under the designation of xe2x80x9cKollidon(copyright)xe2x80x9d with different molecular weights. The same applies to polyvidone acetates, which are available under the designation of xe2x80x9cKollidon VAxe2x80x9d.
In another embodiment of the present invention, the extracts further contain a second carrier selected from carriers which are insoluble in alcohol, insoluble in water or swellable in water and solid at room temperature, or alkaline earth metal and/or alkali metal carbonates including hydrogencarbonates.
The second carrier is preferably selected from carbonates, such as sodium hydrogencarbonate, calcium carbonate or magnesium carbonate, and water-swellable organic polymers, especially starch, starch derivatives, cellulose, cellulose derivatives; cross-linked cellulose derivatives being particularly preferred. Similarly, particularly preferred second carriers are cross-linked polyvinyl pyrrolidone derivatives which are commercially available, for example, under the designation of xe2x80x9cKollidon(copyright)Clxe2x80x9d or xe2x80x9cPolyplastonexe2x80x9d. Thus, effervescent tablets or drinking tablets can also be prepared using disintegrants or effervescent agents per se known in the prior art.
It is particularly preferred according to the present invention if the weight ratio of the second carrier to the first carrier is from 30:1 to 1:1, more preferably from 10:1 to 3:1.
According to the present invention, the medicinal plants are preferably selected from sabalfructus (palmetto fruit), Passiflora, chaste-tree (Vitex agnus-castus), Crataegus, kava, ginkgo, nettle, holy thistle, Hypericum, valerian, Cimicifuga root or rootstock and/or Cynara.
The term xe2x80x9csoluble in alcoholxe2x80x9d as used herein means solubility in methanol, ethanol or 2-propanol, with heating, if necessary. Fluid extracts are often prepared using these solvents. Additionally, however, extraction with other solvents, such as acetone, acetone-water mixtures, or extraction with supercritical steam or carbon dioxide is also known. The term xe2x80x9csolubilityxe2x80x9d is differently defined in different pharmacopoeias. According to the present invention, an extract is considered soluble if at least 15% by weight of the extract is virtually completely dissolved in the solvent at room temperature or with heating, if necessary.
According to the present invention, it is possible to provide standardized dry extracts exhibiting a defined release in which the weight ratio of the non-volatile extract phase to the carrier is preferably in a range of from 1:10 to 1:0.25, especially from 1:5 to 1:0.6, more preferably from 1:3 to 1:0.7.
If the ratio of extract to carrier is chosen too high, the binding of the extract to the carrier is not sufficient, and thus, optimum release of the active components is not provided.
For the preparation of tablets, effervescent tablets, film tablets, coated tablets, drinking tablets, granules or capsules, per se known further auxiliaries and/or additives are optionally added to the medicinal plant dry extracts or their precursors, the fluid extracts. Thus, when tablets are prepared, the auxiliaries and/or additives may preferably be selected from binders, lubricants, fillers, emulsifiers, wetting agents, transition agents and/or disintegrants.
Fluid extracts are preferably employed. To these extracts is added the carrier material, optionally at elevated temperature. Subsequently, the fluid extract is concentrated to dryness at elevated temperature and/or under vacuum. Fluid extracts within the meaning of the present invention include spissum or dry extracts which are prepared according to per se known methods and redissolved in part or completely using suitable solvents.
The concentration to dryness may also be effected, for example, by spray-drying according to per se known methods or with usual technical equipment, such as spray-dryers or fluidized-bed granulators.
The fluid extracts may be prepared in a simple way by extracting the medicinal plants or the corresponding parts thereof in a suitable solvent. The solvent is preferably selected from acetone, chloroform, ethyl acetate and C1-C4 alcohols, their mixtures with one another and with water. Especially preferred solvents are methanol, ethanol and 2-propanol and their water-free or water-containing mixtures, and especially ethanol/water mixtures. The extraction may be effected in a per se known manner by percolation or multi-step stirring or vortex extraction at room temperature or elevated temperature. In addition to the solvents mentioned, extraction with supercritical carbon dioxide can similarly be employed for the preparation of the raw extracts.
Then, with addition of the carrier and optionally with increasing the temperature and/or under vacuum, the solvent of the extract is removed, and the extract is concentrated to dryness to give a solid or semisolid residue.